My first mind-blowing moment in BotW was peeking down from from the top of a hill and seeing a deep valley with a river to the east and a ridge with a forest to the west. They blended gorgeously into a single landscape but I understood that each option would be a different adventure. It was like choosing the north or east exit in classical Zelda, except this was totally organic, not instantiated, operating over perfectly continuous space. I was ~30 at the time and had been playing open world games since the early 2000s. It blew my mind regardless.
Having played so many games, and having even worked at Nintendo for a good time, I’ve lost my sense of wonder somewhat and I only expect to have a few more moments like that in the rest of my life. Nintendo is nevertheless possibly one of the few companies still capable of pulling it off.